For IBM and its partners, mainframes are back in style.

The Armonk, N.Y., IT giant announced Dec. 19 that nearly 400 of its partners and ISVs have begun to offer more than 1,000 applications based on its System z mainframes that run Linux.

The reason for ISVs turning to Linux-based mainframes vary, but Buell Duncan, general manager of ISV and developer relations at IBM, said the ability to partition Linux in a virtualized environment, as well as a drop in price for mainframes, are fueling the interest.

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The lowest price right now for an IBM mainframe is about $100,000, according to IBM.

"We have recently seen a lot of applications and workloads that are coming back to the mainframe," said Sue Griffin, a spokesperson for Sirius Computer Solutions of San Antonio, Texas. Sirius has been an IBM reseller since 1980 but has only worked with the System z series since 2004. "We see a lot of customers coming back to mainframes because it's pure, it's reliable and it's easy to manage."

For its part, Sirius develops customized applications for its customers. The company has financial services, insurance and government customers that are traditional mainframe users, Griffin said. However, the company has also seen interest in mainframe applications from SMBs (small and midsize businesses).

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Since it has started developing custom applications on System z, Sirius has also found a use for IBM products such as the Parallel Sysplex, a data-sharing technology that enables multiple systems in different locations to share the same systems image. Sirius has used this to develop applications for areas such as disaster recovery.

In surveys of the server market for the third quarter, Gartner and IDC each reported that IBM had been drawing in more revenue thanks in large part to its mainframe business.

IBM itself reported that the number of customers running System z systems with Linux has increased 30 percent compared with the same time last year. IBM has also reported success in having ISVs migrate applications developed on Java and WebSphere onto System z.

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For IBM, Duncan sees the company and its ISVs pushing more and more applications onto mainframes as more SMBs and startups see opportunities for growth.

"Our focus is to actively engage with ISVs who are looking to expand their business opportunities," Duncan said. "We want to drive demand and produce more leads and look for more applications to run on the mainframe. We think we have reached a very significant milestone."